1. Field of the Invention
The present invention relates to an optical modulator holder, an optical device and a projector.
2. Description of Related Art
There has been a well-know projector including a plurality of optical modulator devices that modulate light beams irradiated from a light source in accordance with image information to form an optical image, a color-combining optical device that combines the light beams modulated by the respective optical modulator devices to irradiate them, and a projection optical device that projects the light beams combined by the color-combining optical device in an enlarged manner.
As for the optical modulator device, for example, an optical modulator of an active-matrix drive system having a pair of boards with electro-optic material such as liquid crystal sealed therebetween is typically used. More specifically, the pair of boards of the optical modulator includes a drive board arranged on a light-irradiation side, adapted to apply a drive voltage to the liquid crystal and provided with data lines, scan lines, switching elements, pixel electrodes and the like, and an opposing board arranged on a light-incident side and provided with common electrodes, a black matrix and the like.
An incident-side polarization plate and an irradiation-side polarization plate for transmitting a light beam having a predetermined polarization axis are respectively arranged on the light-incident side and light-irradiation side of the optical modulator.
When the light beam irradiated from the light source is irradiated on the optical modulator, the temperature of the optical modulator tends to rise due to light absorption by a liquid crystal layer as well as light absorption by the data lines and scan lines formed on the drive board and the black matrix formed on the opposing board. Further, a light beam not having a predetermined polarization axis contained in the light beam irradiated by the light source and the light beam transmitted through the optical modulator is absorbed by the incident-side polarization plate and the irradiation-side polarization plate, and therefore the polarization plates tend to be heated.
A projector having such optical elements thereinside disclosed in Reference: JP Hei 01-302386A includes a cooling device with use of a cooling fluid in order to suppress the temperature rise of the optical elements.
More specifically, the cooling device described in the Reference is constructed of a substantially rectangular solid casing with openings on opposing end faces. The openings are respectively covered by glass plates, and thus a cooling chamber for sealing the cooling fluid therein is formed. The previously-mentioned optical modulator, the incident-side polarization plate and the irradiation-side polarization plate are arranged at predetermined intervals in the cooling fluid. With this configuration, the heat generated in the optical modulator, the incident-side polarization plate and the irradiation-side polarization plate is directly radiated to the cooling fluid.
In the cooling device described in Reference, however, it is difficult to install the optical modulators at predetermined positions in the casing, and the positioning accuracy of the optical modulator with respect to the casing is low.
Moreover, the positions of the optical modulators might be displaced with respect to the casing after a long period of use.
If the optical modulators are displaced with respect to the casing as mentioned above, the positions of the optical modulators with respect to the optical axis of the light beam irradiated from the light source are also displaced, and therefore an unwanted light is projected on the screen.